Thaw puff pastry for 40 minutes. Preheat oven to 400º. Unfold pastry on lightly floured surface and roll into an 18x9-inch rectangle. Cut into 18 (3-inch) squares. Press squares into 3-inch muffin cups that have been coated with cooking spray; set aside. In mixing bowl, stir together cheese and milk until smooth. Spoon a rounded teaspoonful into each pastry shell. Top with pieces of bacon and green onion. Bake for 15 minutes or until pastry is golden brown. Makes 18 appetizers.